Telephone system



April 1, 1930. v. s. THARP TELEPHONE SYSTEM Filed July 9, 1928 Patented Apr. 1, 1930 UNITED STATES PATENT OFFICE VICTOR S. THARP, OF ELMHURST, ILLINOIS, ASSIGNOR TO RESERVE HOLDING COM- PANY, OF KANSAS CITY, MISSOURI, A CORIORATION OF DELAWARE TELEPHONE SYSTEM Application filed July 9,

The present invention relates to telephone systems in general, but is concerned more particularly with arrangements for establishing telephone connections over composited 5 toll lines connecting two exchanges. In the embodiment of the invention disclosed herein it is applied to composited toll lines connecting a manual exchange with an automatic exchange.

The object of the invention is to provide improved circuit arrangements which will enable toll operators to signal each other and connections to be supervised over a single Morse leg of a composited trunk line, without interfering with the use of the same Morse leg as a circuit for controlling automatic switches.

One of the features of the invention relates to the novel circuit arrangements by .0 means of which a calling operator, by the op-.

eration of her signalling key located at the megneto exchange, can signal a toll operator located at the automatic exchange, or can, by the operation of her calling device, directively control the automatic switches located at the automatic exchange over the same Morse leg of a composited toll line to complete a connection to an automatic subseribers line.

These and other features of the invention will be apparent from the detailed description of the invention which follows:

Referring now to the drawings which comprise only a single sheet there is shown by means of the usual circuit diagrams sulficient of the apparatus involved in the invention to enable the same to be described and understood.

The-reference character TL indicates a toll line connecting a magneto exchange with an automatic exchange. The apparatus shown to the left of the dotted line includes the equipment individual to the toll line TL at the magneto exchange, while the apparatus to the right includes the equipment individual to the toll line at the automatic exchange. The toll line. TL is one of a number of similar composited toll lines connecting the magneto and automatic exchanges.

The toll lines, such as TL, terminate in Serial No. 291,176.

comprises the line signal drop 5, the visual drop 6 and its associated control relay 3, dial key DK, and signal key SK. The calling device CD is common to the toll lines terminating in the operators switchboard.

The individual equipment of the toll line TL at the automatic exchange comprises a repeater or relay group, a rotary line switch C, and the jack J together with its usual busy, supervisory, and line signal equipment at the toll operators position.

The line switch C is of the well known rotary type in which the wipers have no normal position and move in a forward direction only. The line switch G has access to well known Strowger types of selector or connector switches (not shown) over which connections may be completed to automatic subscribers lines.

Directly below the toll line TL, there is diagrammatically shown a portion of the phantom toll line TL which has individual equipment similar to the toll line TL at both exchanges. It is understood that the phantom toll line TL is superimposed on two similar physical toll lines, one of which is the toll line TL.

The Morse leg comprising conductors 13, 18, and 22 in series is used for controlling the calling, answering, and disconnect supervision on manual to manual calls established over toll line TL, for controlling the automatic switches in manual to automatic calls established over toll line TL, and for controlling the answering and disconnect supervision on such manual to automatic calls; while the Morse leg comprising conductors 16, 19, and 23 in series is used in a similar manner for the manual to manual and manual to automatic calls established over the phantom toll line TL.

The apparatus, having been described more or less in general, will now be described in connection with a detailed description of its operation. For this purpose, it will be assumed that a magneto subscriber whose line terminates at the magneto exchange wishes to converse with an automatic subscriber whose line terminates in the automatic ex change. It will further be asslnned that the operator at the magneto exchange has answered the call and in order to complete the desired connection has inserted the plug of her cord circuit into jack J.

Responsive to the insertion of the plug into jack J a circuit may be traced over the Morse leg for energizing relay 36 in the automatic exchange and relay 3 in the magneto exchange as follows: ground by way of winding of relay 36, normally closed springs controlled by armature 4T, normally closed springs controlled by armature 39, resting contactof armature (SS and said armature, conductor 22, up Jer left hand windings 20 of the composite coils CC, conductor 18, upper windings 14 of the composite coils CC, conductor 13, signal key SK and its resting contact, normally closed springs controlled by the spring 8 of the dial key DK, ack spring 7 and its working contact, resting contact of arm ature 2 and said armature, and winding of marg'aal relay 3 to battery. Relay 3, upon energizing, at armature 2 includes the visual signal 6 in the above traced circuit whereupon the visual signal operates in the well known manner. Helay 36, upon energizing, at armature closes a locking circuit for itself and at armature 52 completes an energizing circuit for line relay 33. Line relay 33, upon energizing, at armature 1-1 connects the upper talking conductors 25 and 57; at armature 42 and its working contact completes an energizing circuit for release relay 3%; and at armature l3 and its working contact completes a circuit for energizing slow to release relay 32. Release relay 34, upon energizing, at armature it and its resting contact opens the circuit of sleeve relay 66 located at the toll position and at its working contact completes the circuit for operating the busy drop (30 at the toll position as well as completing the circuit for energizing the polarizing winding of electro-polarized relay S1. The operation 01" the busy drop 60 informs the toll operator at the toll position that the toll line TL busy. At armature 45 relay 34; completes a loo-ring circuit for itself during the time slow to release relay 32 is energized; at armature l6 prepares the circuit for slow to release series relay 35 as well as slow to pull up relay at armature 0! 4:7 and springs 48 and 49 prepares a holding circuit for relays 32 and 323 as well. as opening the original energizing circuit of relay 3t); and at armature 50 connects the talking conductors 26 and thereby closing a bridge across the conductors 57 and 58 for causing the operation of the rotary line switch C. Slow to release relay 32, upon energizing at armature lO completes the locking circuit for release relay 34.

The circuit for initiating the operation of line switch C may be traced as follows: ground by way of the resting contact of ar armature on the line switching relay of the line switch C and said armature (not shown), conductor 58, armature 50, conductor 26,

'inding of impedance coil 30, lower winding of electro-polarized relay 31, conductor 25, armature ll, conductor 57, armature and its resting contact on the switching relay of the line switch C, and through the winding of the line relay of line switch C to battery. The line switch C now operates in the well known manner to select an idle trunk extending to an idle selector or connector switch in order to permit the calling operator to complete the connection to the automatic subscriber. T he electro-polarized relay 31 does not energize at this time because the flow of current through its lower winding is in the wrong direction.

The calling operator now operates her dial key DK thereby connecting ground at the callin device CD instead of the 24 volt battery through relay 3 to the Morse leg of the toll line TL. Responsive to this operation relay 36 at the automatic exchangedeencrgizes and at the normally closed springs controlled by armature 52 maintains the circuit of relay 33 intact over the Morse leg. Relay 36, upon deenergizing, at armature 53 opens its own locking circuit before the normally closed springs controlled by armature 52 are permitted to close thereby preventing a lock up between relays 33 and 36. The circuit for maintaining line relay 33 energized may be traced as follows: from ground by way of the interrupter springs of the calling device CD. spring 8 and its working contact of the dial key DK, normally closed springs of the signal key SK, conductor 13 and over the Morse leg previously t aced to springs 48 and armature 47, and thence by way of armature fr and the normally closed springs controlled by armature 52 to the winding of line relay 233 and battery.

The operator may now dial the number of the automatic subscriber in the automatic exchange. By the operation of toe calling device the circuit of line relay 33 is intermittently interrupted and said relay accordingly energizes and deenergizes responsive thereto. Each time line relay 353 dccnergizes an impulse of current is transmitted to relays 35 and 37 by way of armatures 41:2 and 4.6. clay 37 being a slow to energize relay is not encrgized at this time because the duration of the impulse of current is not long enough to ca use said relay to be fully energized. Relay 35, however, energizes and remains in energized position during each series of impulses and said relay at armature 51 short circuits the right hand windings of the repeating coil BC, the impedance coil 30, and the lower winding of electro-polarized relay 31 in order to provide a more ellicient dialling circuit for the automatic switches in the automatic exchange. T he dialling circuit extends by way of the lower winding of the line relay of the seized switch, line switch wiper, conductor 58, armature 50, armature 51, impulse armature 41, conductor 5'7, wiper of line switch C, and through the upper winding of the line relay of the seized switch to battery. Line relay 33 at armature 41 repeats the impulses over the impulsing circuit just tracel for operating the automatic switches to complete the connection in the well known manner. Although the circuit of slow acting relay32 is intermittently interrupted by the line relay said relay 32 does not deenergize on account of its slow to release characteristics.

After dialling the called number the calling operator restores the dial key DK to normal position and substitutes the 24 volt battery through relay 3 for ground at the calling device. Line relay 33 is maintained over the Morse leg on accountof the difference in battery potential between the two exchanges in which the battery potential at the magneto exchange is 24 volts while the battery potential at the automatic exchange is from 46 to 48 volts. Visual 6 is operated in series with the line relay 33 in order to provide supervision to the calling operator. When the called party answers the flow of current over conductors 57 and 58 is reversed by the back bridge relay in the connector in the well known manner thereby causing the operation of electro-polarized relay 3 1. Electro-polarized relay 31, upon energizing, at armature 39 and its working Contact closes a circuit for maintaining line relay 33 in energized position. At the normally closed contacts controlled by armature 39 relay 31 opens the Morse leg thereupon causing the deenergization of relay 3 and the visual 6 in the magneto exchange. By the restoration of the visual 6 at the magneto board themagneto operator will be informed when the called man has answered.

\Vhen the called man hangs up after conversation the backbridge relay in the connector reverses the flow of. current to normal and electro-polarized relay-31thereupon deenergizes. Relay 31, upon deenergizing, at armature 39 again closes the Morse leg and aga1n causes the operation of relay 3 and visual 6. By the operation of the visual 6 the magneto operator will be informed that the called man has hung up his receiver. The, calling open ator thereupon removes the plug of her cord circuit from the jack J, thereby connecting ground through the high resistance line signal 5, instead of battery through the relay 3 to the Morse leg. Line relay 33 at the automatic exchange deenergizes on account of the high resistance of line signal 5. Line relay 33, upon deenergizing, at armature 41 opens the loop circuit for maintaining the automatic switches in operated position whereupon the line switch C and automatic switches in the automatic exchange are released in the well known manner; at armature 42 opens one of the circuits of relay 34 and at its resting contact sends a momentary impulse to relays 35 and 37 which at this time, however, is without effect; at armature 43 opens the circuit of relay 32 whereupon said relay releases and opens the circuit of relay 34. Relay 34 accordingly deenergizes and returns its armatures to normal position. All of the apparatus in both exchanges are now innormal position and may be used for extending other calls.

Having described the operation of the apparatus involved in a connection from the magneto exchange to an automatic subscriber in the automatic exchange, a description will now be given of the operation of the ap paratus when the operator at the magneto exchange wishes to signal the toll operator located at the automatic exchange instead of operating the automatic switches. The calling operator at the magneto exchange will plug into jack J in the same manner as before and again energize relay 36 over the Morse leg. In the same manner as previously described, relay 33 and then relays 34 and 32 energize. The calling operator will now operate the signalling key SK instead of the dialling key whereupon by the operation of the signal key SK the high resistance 10 is included in the Morse leg. Due to the high resistance of 10, relays 36 and 33 both deenergize while relay 32 is maintained energized over the Morse leg by way of armature 43 and springs 49 and 48 when line relay 33 deenergizes. Line relay 33, upon deenergizing, at armature 41 opens the loop circuit extending to the automatic switches whereupon said switches release and at armature 42 closes an energizing circuit for relays 35 and 37. Relay 35 ener izes but does not perform any useful function at this time. After an interval of time for which relay 37 is adjusted, said relay energizes and at armature 59 prepares the circuit for sleeve relay 66 at the toll board. At armature 54 relay 37 opens 1 the circuit of line relay 33 and at armature 55 closes an energizing circuit for relay 38 which may be traced in parallel with relay 32 over the Morse leg to the 24-volt battery through the winding of relay 3. At armature I 56 relay 38 closes an energizing circuit for line signal 62 whereupon said signal lights to inform the toll operator of the call. Any time after the operation of relay 37 the magneto operator may restore her signal key SK to normal posit1on because at armature 54 relay 37 opens the circuit of line relay 33.

Then the toll operator answers by inserting the plug of one of her associated cord circuits into jack J sleeve relay 66 operates over the following circuit: ground by way of armature 59, sleeve relay 66, sleeve of jack J and sleeve of the inserted plug to battery. Sleeve relay 66, upon energizing, at armature 67 maintains the busy visual in operated position and at armature 68 and its resting contact opens the circuit of relays 32 and 38. At armature 68 and its working contact, sleeve relay 66 connects the Morse leg to the winding of relay 64 and battery. Relay 64 does not energize at this time because said relay is adjusted not to operate in series with the 24-volt battery at the magneto exchange. Relay 3, however, deenergizes in series with relay 64 and relay 3 at armature 2 causes the restoration of the visual signal 6, thereby informing the calling operator that the toll. operator has answered. \Vhen sleeve relay 66 energized and opened the circuit of relays 32 and 38 said relays deenergize and restore the relay group to normal position. The toll operator may now extend the desired connection in any well known manner.

\Vhen the calling operator at the magneto exchange withdraws her plug after conversation, spring 7 of jack J connects ground through the line signal 5 to the Morse leg in place of battery through relay 3 whereupon the following circuits may be traced tor energizing rela 6 at the toll position: ground through winding of line signal 5, spring '7 and its resting contact, normally closed springs of the dial key DK, normally closed springs of the signalling key SK, conductor 13, over the Morse leg by way of ari'nature 68 and its working contact through the winding of relay 6 1- to battery. Bela-y 64 energizes over the above traced circuit and at armature 65 closes a circuit for lighting the supervisory lamp 61 thereby informing the toll operator that the calling operator at the magneto exchange has disconnected her plug from the jack J. The toll operator will thereupon remove her plug from jack J thereby restoring the sleeve relay 66, relay 6%, busy visual 60, and supervisory lamp 61 to normal.

In case, however, the toll operate at the automatic exchange is the first to disconnect, sleeve relay 66 will deonergize when the toll operator removes her plug from jack J Sleeve relay 66, upon dcenergizing, at armature 67 opens the circuit of the visual signal 60 whereupon the busy visual returns to normal position; and at armature 66 opens the circuit of relay 6 1 and again establishes the normal circuit over the lvlorse leg to r lay 36. Relay 64:, upon deenergizin at arnie-iture 65, opens the circuit of the super :ory lamp 6?. hen ground through relay 36 is sub: over the Morse leg for battery through 64 when the toll operator removes her ej, relay 3 at the magneto exchange cue and again causes the operation the ual signal 6, thereby inform ng the operator that the toll operator has disconnected. The calling operator thereupon removes her plug from jack J, thereby restoring the apparatus to normal position.

Having described the operation of the appmfatus in a connection from the operators position at the magneto exchange to the toll position at the automatic exchange, a description will now be given of the operation oi. the appa "atus involved in a connection from the toll. operators position at the automatic exchange to the operators position in the magneto exchange. When the toll operator insert-s the plug of one of her cord circuits into ck J a circuit for energizing sleeve relay 66 may be traced as follows: ground by way oil? armature i l and its resting contact, winding of sleeve relay 66, sleeve of jack J and sleeve of the inserted plug to battery. Sleeve relay 66, upon el'iergizing, at armature 67 causes the opeartion of the busy visual 60 and at armature 68 and its working contact closes a circuit for energizing relay 3 and line signal 5 at the magneto exchange as follows: ground by way of winding of line signal 5, resting contact of jack spring 7 and said spring, normally closed springs controlled by dial key DK, normally closed springs controlled by signal key SK, conductor 13, and over the Morse leg to armature 68 and winding of relay 64; to battery. Line signal 5 and relay 6% both operate. Relay 64 at armature 65 again lights the supervisory lamp 61. The operation of the line signal 5 at the magneto exchange informs the operator thcreat of a call whereupon the operator inserts the plug of. one of her cord circuits into jack J. Rcsponsive to the insertion of: the plug in the jack J, battery through relay 3 is substituted for ground through line signal 5 whereupon relay 6& at the toll position deenergizes and puts out the supervisory lamp 61. As soon as the supervisory lamp 61 goes out the toll operator is aware of the fact that the magneto operator has answered the call whereupon the toll operator will inform the magneto opcrator of the desired connection. The magneto opcartor will then complete the desired connection in any well known manner. After the conversation, the operators will remove their plugs from the jacks J and J whereupon the apparatus is returned to normal position in the same manner as previously described.

Having described the invention, its utility and operation, what is considered new and desired to have protected by Letters Patent will be set forth in the appended claims.

What is claimed is:

1. In a telephone system wherein two-way manual to manual telephone connections are established over a two-way trunk line com prising only two conductors connecting a first and a second exchan e, a control circuit in cluding only one of said conductors, and means controlled over said control circuit whereupon operators at said exchanges can call each other in initiating the manual to manual telephone connections and can signal each other on answering and disconnecting on such calls.

2. In a telephone system wherein two-way manual to manual telephone connections are established over a two-way trunk line comprising only two conductors connecting a first and a second exchange, a control circuit including only one of said conductors, signals associated with said trunk line at both exchanges, and means for controlling said signals over said control circuit to provide calling, answering, and disconnect supervision at each exchange for the manual connections set up over said trunk line.

3. In a telephone system wherein two-way manual to manual telephone connections and one-way manual to automatic telephone connections are established over a composited trunk line comprisin only two conductors connecting a first anc a second exchange, a control circuit or Morse leg including only one of said conductors, and means controlled over said Morse leg whereby operators at said exchanges can call each other for establishing the manual to manual telephone connections and whereby the operator in the first exchange can establish the manual to automatic telephone connections to automatic subscribers in the second exchange.

4. In a telephone system wherein two-way manual to manual telephone connections and one-way manual to automatic telephone connections are established over a composited trunk line comprisin only two conductors connecting a first an a second exchange, a control circuit or Morse leg including only one of said conductors, a call signal and a supervisory signal associated with said trunk 'line at each exchange, and means whereby operators at said exchanges control the operation of said signals over said Morse leg in establishing the manual to manual telephone connections and whereby the called automatic subscribers in the manual to automatic telephone connections control the operation of the supervisory signal at the first exchange over said Morse leg.

5. In a telephone system, two exchanges, a composited toll line comprising only two conductors connecting said exchanges, a control circuit or Morse leg including only one of said conductors, signals associated with said toll line at both exchanges, means for controlling said signals oversaid Morse leg to provide calling, answering, and disconnect supervision at each exchange for manual connections set up over said toll line, automatic switches at the second exchange, means responsive to impulses transmitted over said Morse leg for operating said switches to establish manual to automatic connections from the first exchange to automatic subscribers lines in the second exchange, and means controlled over said Morse leg for operating the signal at the first exchange to give answering and disconnect supervision on the manual to automatic connections.

6. In a telephone system, a composited toll line comprising only two conductors connecting a first and a second exchange, a control circuit or Morse leg including only one of said conductors, automatic switches and a toll operators position at the secondexchange, a first and a second device included in the Morse leg at the first exchange, and means in the second exchange controlled over said Morse leg for signalling the toll operator or for operating said automatic switches to extend a connection to a called subscribers line dependent upon whether the first device or the second device is operated.

7. In a telephone system, a composited toll line comprising only two conductors connecting a first and a second exchange, a control circuit or Morse leg including only one of said conductors, two branches of said toll line at the second exchange, the first of said branches terminating in a toll operators position at the second exchange and the second of said branches terminating in an automatic hunting switch, means controlled over the Morse leg responsive to the seizure of said tollline at the first exchange for operating said switch, a device included in the Morse leg in the first exchange, and means con trolled over the Morse leg in case said device is operated for signalling the toll operator at the second exchange and for disconnecting said switch from said toll line.

8; Ina telephone system, a composited toll linecomprising only two conductors connecting an operators position in a first exchange with a second exchange, said toll line terminating in'two branches at the second exchange, the first of said branches terminating in a toll operators position and the second branch terminating in a repeater and associated automatic hunting switch, a control circuit or Morse leg including only one of said conductors, means controlled over the Morse leg responsive to the seizure of said to'll lineat the first exchange for causing said repeater to initiate the operation of said hunting switch and responsive to impulses transmitted over the Morse leg for causing said repeater to repeat such impulses, a device included in said Morse leg at the first exchange, means controlled over said Morse leg in case said deviceis operated for signalling the tolloperator at the second exchange and for causing said repeater to operatively disconnect said switch from said toll line,and means controlled by the response of the called toll operator for disconnecting said Morse leg from said repeater.

9. In a telephone system, a first exchange, a second exchange, atwo conductor trunk line terminating in the first exchange in an o rators position and in the second exc ange in two branches, the first of said branches terminating in an operators position at the second exchange, automatic switches at the second exchange for extending the second of said branches into connection with called automatic subscribers lines, a control circuit including only one of said conductors, a signalling key included in said control circuit at the first exchange, means controlled over said control circuit responsive to the seizure of said trunk line by the operator at the first exchange for preparing said switches for operation and responsive to impulses transmitted over said control circuit for operating said switches to complete a connection to a called automatic sub scribers line, and means controlled over said control circuit in case said key is operated for signalling the operator at the second exchange and for disconnecting said switches from said trunk line.

10. In a telephone system, a first exchange, a second exchange, a two conductor trunk line terminating in the first exchange in an operators position and in the second exchange in two branches, the first of said branches terminating in an operators position at the second exchange, automatic switches at the second exchange for extending the second of said branches into connection with called automatic subscribers lines, a control circuit including only one of said conductors, a signalling key included in said control circuit at the first exchange, means controlled over said control circuit responsive to the seizure of said trunk line by the operator at the first exchange for preparing said switches for operation and responsive to impulses transmitted over said control circuit for operating said switches to complete a connection to a called automatic subscribers line, means controlled over said control circuit in case said key is operated for signalling the operator at the second exchange and for disconnecting said switches from said trunk line, a signal at said first operators position, and means controlled over said control circuit for operating said signal to indicate the unanswered, answered, and disconnected condition of the called automatic subscribers line or the unanswered, answered, and disconnected condition at the called operators position.

11. In a telephone system, a first exchange, a second exchange, a two conductor trunk line terminating in the first exchange in an operators position and in the second exchan e in two branches, the first of said branc es terminating in an operators position at Y the second exchange, automatic switches at the second exchange for extending the second of said branches into connection with called automatic subscribers lines,

a control circuit including only one of said conductors, a signalling key included in said control circuit at the first exchange, means controlled over said control circuit responsive to the seizure of said trunk line by the operator at the first exchange for preparing said switches for operation and responsive to impulses transmitted over said control circuit for operating said switches to complete a connection to a called automatic subscribers line, means controlled over said control circuit in case said key is operated for signalling the operator at the second exchange and for disconnecting said switches from said trunk line, a signal at said first operators position, means controlled over said control circuit for operating said signal to indicate the unanswered, answered, and disconnected condition of the called automatic subscribers line or the unanswered, answered, and disconnected condition at the called operators position, a supervisory signal at said second operators position, and means controlled over said control circuit for operating said supervisory signal to in dicate the answered and disconnected condition at the first operators position.

In witness whereof, I hereunto subscribe my name this 3d day of July, A. D. 1928.

VICTOR S. THARP. 

